Nikon 58mm f/1.2 Noct-NIKKOR — Bokeh & Optical Ray-Tracing Simulator

Interactive 3D portrait ray-traced through the published US4621909A optical prescription (7 elements in 6 groups) with a 48.3 mm entrance pupil and 0.5 m minimum focus.

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Optical & Portrait Specifications (Upper Body Framing)

Optical & Portrait Metric Measured / Patent Value What It Means in Practice
Patent Prescription US4621909A · 7 elements in 6 groups Traced surface by surface in WebGL2
Entrance Pupil Diameter 48.3 mm (at f/1.2) Controls distant background blur disc size
Corner Bokeh Roundness (90% Field) 66% at f/1.2 (≥86% from f/1.8) · -0.8 EV Mechanical vignetting (cat’s-eye vs. round corner highlights)
Background Field of View (Compression) 34° horizontal Width of the background room visible behind the subject
Upper-Body Working Distance 2.33 m Camera-to-subject distance for head-to-waist framing
Effective Focal Length (Breathing) 58.0 mm (-0.0%) Actual framing focal length at portrait distance
Depth of Field (Sharp Zone) 17 cm (2.25 m – 2.42 m) Sharp zone at wide-open aperture
Minimum Focus Distance 0.5 m Closest focusing distance from the sensor

Questions

How much background blur and corner cat's-eye does the Nikon 58mm f/1.2 Noct-NIKKOR produce?

Wide open at f/1.2, the Nikon 58mm f/1.2 Noct-NIKKOR has a 48.3 mm entrance pupil (58 mm ÷ 1.2) and 66% bokeh roundness in the 90% corner (-0.8 EV corner falloff, reaching ≥86% roundness from f/1.8). In an upper-body portrait at 2.33 m, the sharp depth-of-field zone spans 17 cm (2.25 m to 2.42 m) with a 34° horizontal background angle of view.

Does the Nikon 58mm f/1.2 Noct-NIKKOR show focus breathing at portrait distance?

Based on patent US4621909A, tracing the focusing group at 2.33 m gives an effective framing focal length of 58.0 mm (-0.0% vs. the nominal 58 mm). You can toggle "Match subject size" in the simulator to see the framing shift live.

What optical design is inside the Nikon 58mm f/1.2 Noct-NIKKOR?

The patent prescription (US4621909A) specifies 7 lens elements in 6 groups. The interactive Optical X-Ray above traces rays through every surface in real time.

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Also see: depth of field, bokeh, crop factor, lens compression.